In 1959 Tom Lehrer recorded his notorious “Poisoning Pigeons in the Park” song. I hope no one does that intentionally but many birds die each year from ingesting toxins.
A recent study indicates that two-thirds of California Condor fatalities result from ingesting led shot from the ground or as part of the carrion they ate. In the condors’ range in California, lead shot is banned but around the Grand Canyon, lead shot is the leading cause of their death. Although lead shot poisoning of waterfowl was discovered in 1880, it wasn’t until 1991 that the U.S. Fish and Wildlife Service banned it for hunting waterfowl. But lead shot is still around and 2700 Trumpeter Swans died from eating it in northern Washington State and British Columbia over the past decade.
According to the Cornell Laboratory of Ornithology, at least seven million birds a year are killed by pesticides. The USFWS states that “birds exposed to lawn chemicals may exhibit symptoms including shivering, excessive salivating, grand mal seizures, wild flapping and even screeching.” When I was working people brought me sick birds exhibiting these systems, especially in the spring when pesticides are most often applied. It is easy to blame ranchers and farmers, but homeowners are more responsible than they might imagine. The average homeowner applies ten times as much pesticide as is necessary to control household and lawn pests. Is it really necessary to spray for spiders and ants or earwigs? (I used to have a neighbor who sprayed every individual weed in his yard with a large tank of herbicide strapped to his back. He just didn’t want to bend over to pluck the green offenders.)
Poisons are used both legally and illegally to kill rodents and predators such as coyotes. Unsuspecting birds either eat the bait or the carcass of the dead predator; 756 Bald Eagles died this way last year, accounting for 36 percent of all eagle deaths (in second place with 22 percent of fatalities was shooting.)
The most famous real bird poisoning and a fictional story were morphed into a movie by Alfred Hitchcock in 1963. The Birds was based on a 1952 short story by Daphne du Maurier. Supposedly, Ms. du Maurier got the idea of birds attacking in a frenzy after she observed a farmer plowing his field with gulls harassing him. In her story, lots of birds of different species went on a rampage. As Hitchcock was planning the film he read in the Santa Cruz Sentinel about Sooty Shearwaters acting crazy. The birds flew all over town, regurgitated fish, ran into buildings and lamp posts and died in the streets. There have been many more incidents like this although not nearly as famous. Recent evidence reveals the cause: diatoms, a kind of algae with a silicon shell, produce a toxin called domoic acid, which can cause confusion, disorientation, seizures and death. As it moves up the food chain it concentrates in fish which are then eaten by birds.